As mentioned earlier, the Mail app supports multiple email accounts at the same time, so feel free to add in all the accounts you need to keep track of. The Mail app will handle the rest.
Coming to the usability of the Mail app, you can freely compose emails, respond to emails, mark them as important, and also shift unwanted emails to the trash. Basically, everything that you need to do with your mailbox, can do it on the Mail app on macOS.
